1. Field of the Invention
The present invention relates generally to support devices for the human body and more particularly to an improved inflatable belt worn during the lifting of heavy objects such as weights.
2. Related Art
Those who lift heavy objects, for instance, weight lifters, often use belts to help support their spine and back muscles while lifting such objects. The belts commonly employed attempt to provide specific support to the lumbar area of the spine. However, inherent difficulties arise due to the materials from which such belts are manufactured. The belts are usually made from a thick strip of stiff leather. Although leather provides firm support, its inflexibility prevents it from providing uniform surface contact with the lumbar area of the spine. As a result, belts made entirely from leather do not provide uniform support to the curved spinal areas of the back, and particularly the lumbar or arch region of the back.
An example of a conventional weight lifting belt is shown in FIG. 2 of U.S. Pat. No. 4,348,774 to Woodson. In this belt, the central portion is enlarged in comparison to the end portions of the belt to provide a wider base of support to the spinal region of a wearer. The Woodson patent describes the addition of a thin layer of foamed, flexible plastic on the inner surface of the belt to protect the wearer against chafing. Because the liner is thin and has uniform thickness, the amount of support which the liner provides to the lumbar area of the spine is dependent upon how tightly the wearer cinches the belt about his or her waist. However, even if the belt is pulled as tightly as possible, the thin, foamed layer still may not completely support a particular wearer's spine due to the dimensional variations that are possible in the curvature of the lumbar region of the body.
Thus, further development in the technology has been directed toward providing specific support in the lumbar spinal region of the back. For example, U.S. Pat. No. 4,905,993 to Barone describes a weight lifting belt designed to provide direct localized support of the lower spine by providing a narrow pad constructed of high density foam shaped to fit into the "indentation" of the spine. However, the narrow width and the fixed shape of the pad could actually create an area of concentrated pressure against the spine so localized as to be uncomfortable.
Accordingly, attempts have been made to provide improved lumbar support while accommodating the variations in the profile of the human lumbar spinal region. At least one has attempted to provide customized lumbar support by replacing the fixed-shape pad with a centrally-located fluid-filled pad. For example, U.S. Pat. No. 4,968,027 to Anderson describes a weight lifting belt having a lumbar support in the form of a moldable gel. While the gel does conform to fit, in part, the lumbar region of a user's back, the fluid-filled pad is of constant volume. A constant-volume pad is still unable to provide variable support to the lumbar spinal region independent of tightly cinching the belt about the user's waist.
Others have tried to use an adjustable-volume fluid-filled bladder; for example, U.S. Pat. No. 4,552,135 to Racz et al. describes a support belt having a centrally-located pad including a chamber filled with open-cell sponge-like material. A valve connects the chamber with the atmosphere and controls the flow of air into and out of the chamber. The valve provides the advantage that the chamber is adjustable to fit an individual's spinal curvature. However, due to loss of air pressure in the chamber from unavoidable diffusion resulting from use, the belt must be removed from the body in order to reinflate the chamber. This is because air is drawn into the chamber only when the sponge-like material forces the walls of the chamber apart which occurs only by relieving the compression forces exerted by the wearer's body on the chamber. Thus, the wearer must repeatedly take off the belt to reinflate as pressure is lost during use.
Therefore, others have attempted to provide a belt that is inflatable while the belt is worn to satisfy the dual goals of providing a support device capable of being adjusted even after the belt is worn as well as providing a support device which can accommodate for the dimensional variation in the curvature of the lumbar region of the human body.
For example, U.S. Pat. No. 1,646,590 to Mildenberg; U.S. Pat. No. 4,178,923 to Curlee; U.S. Pat. No. 4,703,750 to Sebastian et al.; and U.S. Pat. Nos. 4,993,409 and 5,062,414 to Grim all describe associated mechanisms for inflating belts with bladders. Some, such as the Mildenberg patent provide for the bladder to be pressurized by the wearer's blowing into a conduit attached to the bladder. Not surprisingly, the wearer's act of tightening and expanding the muscles of the diaphragm of the body to pressurize the bladder could make blowing air into the bladder more difficult.
Others describe inflation mechanisms such as mechanical pumps which are removably attached to the associated belt. Not only is this arrangement inconvenient in that it requires that the user have the separate pump nearby during use to quickly accommodate for diffusion, but it also requires the provision of at least one conduit to communicate fluid between the pump and the bladder, which adds to the manufacturing costs and propensity for fluid leakage.
Others, such as U.S. Pat. No. 4,135,503 to Romano; U.S. Pat. Nos. 4,178,922; 4,622,957; 4,682,588; and 4,756,306 to Curlee; U.S. Pat. No. 4,836,194 to Sebastian et al., and U.S. Pat. No. 5,195,948 to Hill et al. all describe belts which incorporate an inflation mechanism permanently attached to the belt. While this arrangement does eliminate the inconvenience of having to have a separate inflation mechanism handy when using the belt, all of these patents still require the use of a separate conduit between the pump and the bladder.
Further, several of these patents also describe bladders having multiple pneumatic chambers and bladders having complex geometrical profiles. A bladder having multiple pneumatic chambers provides less ultimate volume than a bladder having the identical profile with a single pneumatic chamber. A single pneumatic chamber having greater ultimate volume has enhanced potential for providing customized fit.
Multiple pneumatic chambers also require additional tooling expense in manufacturing as does a bladder having a complex geometrical profile.
Thus, the need exists for a belt which provides lumbar support, but avoids the "localized pressure effect," which is capable of being adjusted independent of tightly cinching a belt about a wearer's waist, which can accommodate the wide variation in the dimensions of the lumbar spinal region of the human body, which does not require a separate conduit for communication between an inflation device and a bladder, which has an inflation device fixed on the belt, which has a bladder constructed to have a single chamber, which has a bladder with a simple geometry, and which may be constructed with a minimum of manufacturing cost.